Split flex cable

ABSTRACT

A cable assembly for interconnecting a plurality of circuit boards together by using a connector assembly connected to each of the circuit boards. The cable assembly includes a first cable having a first end part and a second cable having a second end part. A first periphery of the first end part has a plurality of first half vias that collectively form a column along a width direction of the connector assembly. A second periphery of the second end part has a plurality of second half vias that collectively form a column along the width direction of the connector assembly. The first and second end parts are coupled together to form a connecting unit, such that the first half vias and the second half vias are joined together to form full vias.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a flex cable for interconnecting together aplurality of printed circuit boards through a connector assembly, and inparticular, to a split flex cable that is coupled to the connectorassembly, thereby providing an increased electrical performance andenhanced mechanical flexibility.

2. Background Information

Cables typically are coupled with an electronic connector assembly atopposing ends that are matable with a printed circuit board ofelectronic devices. Such a cable connector assembly is well known in theconnector assembly art and includes a universal serial bus (USB)-typeconnector assembly, a parallel connector assembly, a serial connectorassembly, a VHDM (very high density metric) connector assembly, and thelike. The VHDM connector assembly may be used for a high-densityconnection between electronic devices.

In computer systems, for example, flex cables having connectorassemblies at each end are utilized for a high-speed interconnectionbetween a first circuit board assembly and a second circuit boardassembly. However, when a single flex cable interconnects more than twocircuit boards, the end of the flex cable should be understood to meaneach portion of the flex cable that is connected to each printed circuitboard through the VHDM connector assembly.

FIG. 1 illustrates a conventional flexible or flex cable incorporatedwith VHDM connector assemblies for interconnecting two circuit boards. Aflex cable 10 and two connector assemblies 12 a and 12 b (hereafter maybe referred to as 12 for simplicity) jointly interconnect together afirst circuit board 14 and a second circuit board 16. Each of thecircuit boards 14 and 16 may be a portion of a separate computer system.The connector assembly 12, for example a VHDM connector assembly, iselectrically and mechanically coupled to connecting portions of the flexcable 10 through vias, such as by soldering or the like.

FIG. 2 is a schematic plan view of a conventional VHDM connectorassembly. The VHDM connector assembly 12 has signal pins that areschematically shown from a plan view of the VHDM connector assembly 12and labeled by a row designation (A-H) and a column designation (1−N).These signal pins are connected to the flex cable 10 and also receivedin sockets (not shown) of corresponding mating connectors (not shown) onthe circuit boards 14 and 16. The connector assembly 12 has a limitednumber of signal pins arranged along a width direction W of theconnector assembly 12, and thus has a predetermined number of rows(e.g., eight rows in FIG. 2). In contrast, the VHDM connector assembly12 may have, in its length direction L, as many columns of signal pinsas required.

Each column of signal pins is separated from adjacent columns of signalpins by ground shield GS. Each ground shields GS has a predeterminednumber of ground shield solder tails or ground pins (not shown) that arearranged along the width direction W of the connector assembly 12. Theconnector assembly with eight-row signal pins conventionally has sevenrows of ground pins shown as dotted circles in FIG. 2.

The signal pins and ground pins of the connector are inserted intocorresponding vias of the flex cable that are arranged in a pattern thatthe pins of the VHDM connector assembly 12 can be inserted into to thevias.

Each connecting portion 110 and 120 of the flex cable 10 has a pluralityof signal vias and a plurality of ground vias. For example, as shown inFIG. 3, the connecting portion 110 has eight signal vias A-H in eachsignal column and seven ground vias J-P in each ground column, so as tocorrespond to the pins of the VHDM connector assembly 12. The signalcolumn and ground column are alternately disposed and respectivelyextend along a width direction of the flex cable 10.

Conventionally, a VHDM connector assembly is connected to only onesingle connecting portion of a flex cable that extends and integrallyformed in its length direction L. FIG. 4 shows the flex cable 10 and theVHDM connector assemblies 12 of FIG. 1 with the flex cable 10 andconnector assemblies being connected to each other. The VHDM connectorassembly 12 a is coupled only to a first connecting portion 110 of theflex cable 10, and the VHDM connector assembly 12 b is coupled only to asecond connecting portion 120 of the flex cable 10. Each connectingportion 110 and 120 is integrally formed in its length direction.Accordingly, the single flex cable 10 interconnects the two circuitboards 14 and 16 through the connector assemblies 12 a and 12 b.

In case of a complex system, more pins are required in the VHDMconnector assembly, and a large number of vias and a large length ofsignal wirings are required in the flex cable, resulting a significantincrease in the width of the flex cable or in the number of layers on aflex cable.

For example, if four busses B1 to B4 of signal lines are required tointerconnect the two circuit boards 14 and 16 as shown in FIG. 4, thesefour bus lines B1 to B4 should be included in the single flex cable 10.Each buses may be comprised of a plurality of line, e.g., 16 lines. Thenumber of bus lines that could run on one signal layer of the flex cable10 varies depending on the number of signals in a bus line and theallowable overall width of cable. The number of lines that could run ona single layer also depends on a width of each line and a line-to-linespacing, both of which have signal integrity and manufacturabilitylimit. For example, so as to dispose all of the busses B1 to B4 on asingle layer, a width of the cable WC1 should be increased accordingly.However, such an increased width WC1 may exceed the allowable overallwidth of the flex cable, increase the manufacturing cost, and reduce theflexibility of the flex cable.

Alternatively, the bus lines B1 to B4 of the flex cable 10 may bedisposed on two or more separate signal layers of the flex cable basedon the signal amounts and the constraint for the overall width of cable.However, this configuration also requires increased number of layers ina single flex cable. A higher number of layers on flex cables increasecost, negatively affect manufacturability and reliability, and result inmore stiff cables that do not meet flexibility or other mechanicalpackaging requirements.

FIG. 5 illustrates required number of layers for interconnecting afour-drawer system. A single flex cable 50 connects drawer #1 to drawers# 3 and #4, and drawer #2 to drawers #3 and #4. The single flex cable 50includes buses of lines B51 to B54. Each of lines B51 to B54 represent abus that interconnects drawers #1 and #3, drawers #1 and #4, drawers #2and #3, and drawers #2 and #4. However, so as to dispose those four buslines on a single signal layer, the bus B54 necessarily cross the busesB51 and B52, thereby making it impossible to use a cable with a singlelayer. At least two layers are required in the flex cable 50 forinterconnecting the four-drawer system as shown in FIG. 5. Thisincreased number of layers reduces the flexibility of the flex cable.Further, when the flex cable 50 is configured to have an additionallayer for the bus B54, the bus B54 necessarily crossover the remaininglayer or layers on which other bus or buses are disposed. Thus, the flexcable 50 should have an additional space for such crossovers, resultingan associated bad SI impact on the flex cable 50.

A flex cables that is split along a length direction, e.g., designatedby an arrow L in FIGS. 2 and 3, of the VHDM connector assembly has beendeveloped. See “Modified VHDM connectors and modular flexible circuitryallowing for increased design flexibility and manufacturability” athttp://www.ip.com/pubview/IPCOM000029050D.

However, when the connecting portion of the flex cable is split in itslength direction that is perpendicular to its width direction, eachsplit part of the connecting portion of the flex cable has the samelength in the length direction of the connector assembly to which eachsplit part is connected. Thus, each split part should be formed as anintegrated element that has the same length as an unsplit connectingportion of the flex cable, thereby limiting design flexibility.

In addition, the conventional VHDM connector assembly 12 is, e.g., on a2.0×2.25 mm pitch. Accordingly, the vias of the corresponding flex cable10 has a pitch PL (see FIG. 3) of 2.0 mm in the length direction and apitch PW (see FIG. 3) of 2.5 mm in the width direction. Accordingly,when the connecting portion of the flex cable 10 is split in the lengthdirection L that is perpendicular to the width direction W, the flexcable 10 is split across the 2.5 mm pitch which is wider than the 2.0 mmpitch, thereby limiting the flexibility of the flex cable.

Moreover, such a flex cable split in its length direction does not giveany solution to the layer number increase in the flex cable forconnecting a multi-drawer system.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a cable assembly including asplit connecting unit is provided. The connecting unit is split into twoseparate parts, including a first connecting part and a secondconnecting part. The first connecting part is a portion of a firstcable, and the second connecting part is a portion of the second cable.The first cable further includes a main cable portion and anotherconnecting part. The second cable further includes a main cable portionand another connecting part. The first and second cables jointly connecttwo circuit boards through a connector assembly. The connector assemblymay be a VHDM connector assembly. The first and second connecting partsjointly form the connecting unit connected to the connector assembly.

In another exemplary aspect of the invention, the number of buses in thefirst cable may be the same as or different from the number of buses inthe second cable, on condition that the first and second cables jointlyinclude the required total number of buses for the interconnectionbetween the two circuit boards. The buses of each cable may be disposedon the same layer so as to reduce a thickness of each cable, or may bedisposed on a plurality of layers so as to meet a width restraint ofeach cable. Thus, the numbers of layers of the first cable may be thesame as or different from that of the second cable. The width of thefirst cable may be the same as that of the second cable. Further, themain cable portions of the first and second cables can be stackedtogether in a thickness direction of the cable, so as to reduce a widthof the combined cables.

In a further exemplary aspect of the invention, the connecting unit hasa split line disposed between the two connecting parts. The split lineextends along a width direction of the connecting unit which is the sameas the width direction of the connector assembly, and passes through thecenter of ground vias of one of the ground columns of the connectingunit.

In a further exemplary aspect of the invention, the cable assembly maybe configured to run signals to extend from one connecting part to theother connecting part, crossing over the split line e.g., through viason the split line. The vias may be tied together with solder anddisposed in areas without connector assemblies.

In a further exemplary aspect of the invention, the split line may be ina step shape, a zigzag shape, or other suitable shapes. The step-shapedsplit line may include a first plurality of sub-lines extending alongthe width direction of the connector assembly and a second plurality ofsub-lines extending along the length direction of the connectorassembly. The first sub-lines collectively divide the connecting unit ofthe cable assembly into two separate connecting parts in the widthdirection. The second sub-lines respectively connect two adjacent firstsub-lines. Further, some of the sub-lines may pass through centers ofthe signal vias, while the remaining sub-lines pass through centers ofthe ground vias.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a conventional flex cable to beincorporated with conventional VHDM connector assemblies forinterconnecting two circuit boards.

FIG. 2 is a schematic plan view of the conventional VHDM connectorassembly shown in FIG. 1.

FIG. 3 is a schematic plan view of a connecting portion of the flexiblecable shown in FIG. 1.

FIG. 4 is a schematic plan view, illustrating the connection of the flexcable and the VHDM connector assemblies shown in FIG. 1.

FIG. 5 is a schematic view of the flex cable shown in FIG. 1 connectedto a four-drawer system, illustrating required number of layers of theflex cable for interconnecting the four-drawer system.

FIG. 6 is a partial plan view of a connecting unit including a firstconnecting part and a second connecting part, according to an exemplaryembodiment of the invention.

FIGS. 7A and 7B are schematic plan views of a first cable and a secondcable jointly forming a cable assembly and the connecting unit shown inFIG. 6.

FIG. 8 is a schematic partial plan view of the connecting unit shown inFIG. 6, when the first and second connecting parts are joined togetherwith a split line being disposed therebetween.

FIGS. 9A and 9B are schematic perspective plan view of a cable assemblyfor interconnecting a three-drawer system, according to anotherexemplary embodiment of the present invention.

FIG. 10 is a schematic plan view of a connecting part according to afurther exemplary embodiment of the present invention.

FIG. 11 is a schematic plan view of a connecting part according to afurther exemplary embodiment of the present invention.

FIGS. 12, 14 and 15 are, respectively, a schematic plan view of aconnecting part according to a further exemplary embodiment of thepresent invention.

FIG. 13 is a schematic plan view of a circuit board according to afurther exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in more detail by way of examplewith reference to the embodiments shown in the accompanying figures. Itshould be kept in mind that the following described embodiments are onlypresented by way of example and should not be construed as limiting theinventive concept to any particular physical configuration.

Further, if used and unless otherwise stated, the terms “upper”,“lower”, “front”, “back”, “over”, “under”, and similar such terms arenot to be construed as limiting the invention to a particularorientation. Instead, these terms are used only on a relative basis.

FIG. 6 is a partial top plan view of a connecting unit 60 of a cableassembly, according to an exemplary embodiment of the invention. Theconnecting unit 60 is split into two separate parts, including a firstconnecting part 62 a and a second connecting part 64 a.

Because the two connecting parts 62 a and 64 a are separated from eachother, each connecting part may be formed as a portion of a separatecable. As shown in FIG. 7A, the cable assembly of the invention includea first cable 62 and a second cable 64. The first connecting part 62 ais a portion of the first cable 62, and the second connecting part 64 ais a portion of the second cable 64. The first cable 62 further includesa main cable portion 62 b and another connecting part 62 c. The secondcable 64 further includes a main cable portion 64 b and anotherconnecting part 64 c. The first and second cables 62 and 64 may jointlyinterconnect the two circuit boards 14 and 16 (see FIG. 1) throughconnector assemblies 70 a and 70 b. The connector assemblies 70 a and 70b may be a VHDM connector assembly.

Because the two connecting parts 62 a and 62 b are separated from eachother, each connecting part may be formed as a portion of a separatecable. As shown in FIG. 7A, the cable assembly of the invention includea first cable 62 and a second cable 64. The first connecting part 62 ais a portion of the first cable 62, and the second connecting part 64 ais a portion of the second cable 64. The first cable 62 further includesa main cable portion 62 b and another connecting part 62 c. The secondcable 64 further includes a main cable portion 64 b and anotherconnecting part 64 c. The first and second cables 62 and 64 may jointlyinterconnect the two circuit boards 14 and 16 (see FIG. 1) throughconnector assemblies 70 a and 70 b. The connector assemblies 70 a and 70b may be a VHDM connector assembly.

As shown in FIGS. 7A and 7B, the first connecting part 62 a is connectedto a right portion of the connector assembly 70 a, and the secondconnecting part 64 a is connected to a left portion of the connectorassembly 70 a. The first and second connecting parts 62 a and 64 ajointly form the connecting unit 60 matable with the connector assembly70 a. The remaining connecting parts 62 c and 64 c may be similarlyconnected to a right portion and a left portion of the connectorassembly 70 b, and jointly form another connecting unit 65 matable withthe connector assembly 70 b. The first and second cables 62 and 64jointly form a cable assembly that interconnects the two circuit boards14 and 16 together. More specifically, the end portions of first andsecond cables 62 and 64 jointly form the connecting units 60 and 65,which are respectively matable with the connector assemblies 70 a and 70b.

Four buses are required to connect the two circuit boards 14 and 16, asshown in FIG. 4. Accordingly, in FIGS. 7A and 7B, a combination of thetwo cables 62 and 64 are needed to have the same total number of buses(i.e., four buses) that are required in FIGS. 7A and 7B. FIG. 7Aexemplary illustrates that the first cable 62 has two buses, and thesecond cable 64 has two buses. Due to the same number of buses therein,the first cable 62 and the second cable 64 may be configured to includethe same number of layers. However, the number of buses in each cablemay vary as long as the two cables jointly have the required totalnumbers of buses for the interconnection between the circuit boards.Accordingly, the number of layers in the first cable 62 may be differentfrom those in the second cable 64.

Because each cable 62 and 64 has two buses, each cable 62 and 64 mayhave a reduced width WC2 (see FIG. 7A) compared with the width WC1 (seeFIG. 4) of the cable 10. However, a width of the cable 62 may bedifferent from a width of the cable 64. In addition, as shown in FIG.7B, the main cable portions 62 b and 64 b may be stacked together in athickness direction of the main cable portions, so as to better meetsystem constraints by reducing the width of a combination of the twocable portions 62 a and 64 b.

By connecting two systems with multiple cables, each cable may have areduced number of buses and a reduced width. Further, compared with theconventional cables that may be required to have an increased number oflayers to meet the minimum width constraint of the cable, each cable ofthe invention may have a reduced number of layers. Accordingly, thecable of the invention is more flexible. In addition, each cable may beformed as a modular cable, which is easier to manufacture, therebyimproving yields and reducing the manufacturing cost.

FIG. 8 is a plan view of the connecting unit 60 with the first andsecond connecting parts 62 a and 64 a being joined together as shown inFIG. 7B, for example, by wave-soldering or reflow-soldering across asplit line SL. As shown in FIG. 8, the cable assembly 60 may have eightsignal vias in each signal column, and seven ground vias in each groundcolumn, so as to correspond to the conventional VHDM connector assemblyas shown in FIG. 2. The connecting unit 60 has two parts, i.e., a rightpart 62 a and a left part 64 a, with a split line SL being disposedtherebetween. The split line SL extends along a width direction of theconnecting unit 60 which is the same as the width direction W of theconnector assembly 70 a, and passes through the center of ground vias ofthe ground column.

Each connecting part 62 a and 64 a has semicircular half vias 620 and640 (see FIG. 6). When the two connecting parts 62 a and 64 a arejoined, the two half vias 620 and 640 jointly form a via 660, as shownin FIG. 8. A ground pin (not shown) of the VHDM connector assembly 70 acan be connected with the circular via 660. In this way, a ground shield(not shown) of the VHDM connector assembly 70 a can be connected withthe via 660 or other ground vias in the split zone. Thus, The groundvias in the split zone can be connected to the ground shield of the VHDMconnector assembly 70 a like other ground vias in the remaining portionof the connecting unit 60. Accordingly, a return loop path is providedto a portion of the VHDM connector assembly 70 a connected with thesplit zone similar to all the other portions of the VHDM connectorassembly 70 a, thereby maintaining SI performances. However, even whenno ground pin is inserted into the vias in the split zone, the twoconnecting parts may be joined together to form a single connecting unitby wave-soldering or reflowing-soldering the vias in the split zonetogether.

FIGS. 9A and 9B illustrates a cable assembly according to anotherexemplary embodiment of the invention for interconnecting a three-drawersystem. The cable assembly includes three cables 82, 84 and 86. Thesethree cables 82, 84 and 86 collectively interconnect together threecircuit boards (not shown) through three connector assemblies 90 a, 90 band 90 c that are respectively connected to each circuit board. Thecables 82, 84 and 86 respectively include a first end part 82 a, 84 aand 86 a, a main cable portion 82 b, 84 b and 86 b, and a second endpart 82 c, 84 c and 86 c. The first end parts 82 a and 84 a of thecables 82 and 84 jointly form a connecting unit 83 connected to theconnector assembly 90 a. The second end part 82 c of the cable 82 andthe first end part 86 a of the cable 86 jointly form a connecting unit85 connected to the connector assembly 90 b. The second end parts 84 cand 86 c of the cables 84 and 86 jointly form a connecting unit 87connected to the connector assembly 90 c.

If two buses are required so as to interconnect two circuit boards inthe three-drawer system, each cable has two buses (B11, B12), (B13, 14)and (B15, B16), as shown in FIG. 9A. The two buses of each cable may beformed on a single layer, so as to reduce a layer count. Further, asshown in FIG. 9B, the main cable portions 82 b, 84 b and 86 b may havethe same width, and can be stacked together in its thickness direction,so as to reduce a width WC3 of the combined cables. However, each cableportion may have a different width. According to this exemplaryembodiment of the invention, each set of buses for connecting twocircuit boards is disposed in a separate cable. Degradation of the SIperformance of the flex cable can be prevented, because a bus in onecable may crossover another bus in another cable without vias. In theconventional cable with multiple layers, a signal line in one layershould cross over another layer through additional vias for suchcrossover. However, these additional vias also take space, therebyimpacting cable routing, cable width or layer count.

Next, a method for fabricating the cable assembly of the invention willbe described. The cable assembly may be fabricated by using a flex cablethat generally includes signal lines, frame ground domains and logicground domains. When the flex cable is split into two parts, one partmay form the first connecting part 62 a of the first cable 62, and theother part may form the second connecting part 64 a of the second cable64, as shown in FIG. 6.

First, the signal lines of the flex cable are wired out of the area ofthe flex cable to be split.

Second, the frame ground or power domains are pulled back from the edgeof the area to be split. These frame grounds are pulled back so thatthey are not exposed at the split line SL (see FIG. 8) of the cables 62and 64, thereby preventing a short circuit from occurring between thefirst and second connecting parts 62 a and 64 a.

Third, the logic ground domains are pulled back from the edge or thesplit line SL of the area to be split, or they can extend past the edgeof the routed cable leaving exposed ground planes in the split zone.When the half vias of the two connecting parts 62 a and 64 a aresoldered together later, the logic ground domains of the two connectingpart are interconnected together. In this case, the logic ground domainsof each connecting parts could extend to the half vias of eachconnecting parts 62 a and 64 a.

Fourth, the flex cable is cut or split into two or more separate partsthrough at least one split line that passes through centers of vias,thereby forming, e.g., the first connecting parts 62 a and the secondconnecting parts 64 a, each having half vias at each outer periphery.The vias may be ground vias, and accordingly the half vias may be groundhalf vias. However, the vias may be power vias connected to the powerdomains or signal vias connected to the signal lines, and thus the halfvias may be power half vias or signal half vias.

Fifth, the two or more split separate parts are joined together byaligning. During the joining, the split parts may be laminated onto anFR-4 stiffener.

Finally, the VHDM connector assemblies are attached to the joinedseparate parts by using conventional processes.

The cable assembly of the invention enables a customized volume design.Because the connecting unit of the invention can be divided into aplurality of connecting parts, it is possible to set ID bits of theconnecting unit or fix a defected area in the connecting unit based oneach divided connecting part, without treating the entire connectingunit. As shown in FIG. 10, two connecting parts 110 and 120 are coupledtogether to form jointly a single connecting unit. ID bits of theconnecting unit can be set easily by replacing the part 120 by otherconnecting parts 122, 124 and 126 each of which has required ID bits.Further, the cable assembly of the invention enables an easy replacementof defective segments, by replacing the connecting part 120, whendamaged, with a new connecting part 128.

As shown in FIG. 11, the cable assembly according to another exemplaryembodiment of the invention may be configured to run signals S1 to S3 toboth sides of the split line SL. Each signal S1 to S3 extends from oneconnecting part to the other connecting part, crossing over the splitline SL e.g., through vias on the split line. The vias may be tiedtogether with solder and disposed in areas without connector assemblies.

As shown in FIG. 12, the cable assembly of the invention may havevarious split patterns. A split line SL1 of the connecting unit of thecable assembly extends along the width direction of the connectorassembly, forming a vertical linear split pattern. The split line SL1cut through centers of ground vias.

Further, the connecting unit may have an irregular split line SL2. Thesplit line SL2 include sub-lines SL2 a to SL2 e that collectively form astep shape. However, the split line may be a zigzag shape or othershapes. The sub-lines SL2 a, SL2 c and SL2 e extend along the widthdirection W of the connector assembly, and collectively divide theconnecting unit of the cable assembly into two separate connecting partswith respect to the width direction W. The horizontal sub-lines SL2 band SL2 d respectively connect two adjacent vertical sub-lines (SL2 a,SL2 c) and (SL2 c, SL2 e), and may extend along the length direction Lof the connector assembly.

Further, the split line is not limited to pass through centers of theground vias. In FIG. 12, the sub-lines SL2 b, SL2 c and SL2 d passthrough centers of the signal vias, while the sub-lines SL2 a and SL2 epass through centers of the ground vias.

Further, the split line may have an angle other than 180 degree in thevias. In FIG. 12, the split line SL has a 90 degree angle in the via atwhich the sublines SL2 b and SL2 c are joined together, as well as inthe via at which the sublines SL2 c and SL2 d are joined together.Further, the vias may be split into three or more sections, allowing theflex cable to be split into three or more sections accordingly, therebyincreasing the design flexibility. For example, a via may be split intothree sections by split lines SL1 and SL3 as shown in FIG. 14, and a viamay be split into four sections by split lines SL1, SL2, SL3 and SL4with each section having cut by 90 degrees as shown in FIG. 15.

According to another exemplary embodiment of the invention, a circuitboard connected to the connector assembly may be split into two or moresegments. FIG. 13 illustrates a circuit board 130 to be connected with aconnector assembly. So as to be connected with two different connectorassemblies (not shown) with the same or similar signals, the circuitboard 130 may include two unique segments 135 and 140. The segment 135may be configured to correspond to a first connector assembly (notshown), whereas the segment 140 may be configured to correspond to asecond connector assembly (not shown). The segment 135 or 140 of thecircuit board 130 can be selected depending upon the correspondingconnector assembly. Further, the segments may be formed by cuttingthrough centers of vias 132 of the circuit board. The vias 132interconnect together the circuit board 130 and the segments 135 or 140.

It should be understood, however, that the invention is not necessarilylimited to the specific arrangement and components shown and describedabove, but may be susceptible to numerous variations within the scope ofthe invention.

It will be apparent to one skilled in the art that the manner of makingand using the claimed invention has been adequately disclosed in theabove-written description of the preferred embodiments taken togetherwith the drawings. It will be understood that the above description ofthe preferred embodiments of the present invention are susceptible tovarious modifications, changes, and adaptations, and the same areintended to be comprehended within the meaning and range of equivalentsof the appended claims.

1. A cable assembly for interconnecting a plurality of circuit boardstogether by using a connector assembly connected to each of the circuitboards, the connector assembly having a plurality signal pins and aplurality of ground pins disposed in a plurality of columns, each columnextending in a width direction of the connector assembly, the cableassembly comprising: a first cable having a first end part connected tothe connector assembly, the first end part having vias for receiving thesignal pins and the ground pins, the vias being disposed to correspondto various ones of the signal pins and the ground pins, a firstperiphery of the first end part having a portion that has a plurality offirst half vias that collectively form a column along the widthdirection of the connector assembly; and a second cable having a secondend part connected to the connector assembly, the second end part havingvias for receiving the signal pins and the ground pins, the vias of thesecond end part being disposed to correspond to various other ones ofthe signal pins and ground pins, a second periphery of the second endpart having a portion that has a plurality of second half vias thatcollectively form a column along the width direction of the connectorassembly, wherein the first periphery of the first end part and thesecond periphery of the second end part are coupled together, such thatthe first half vias and the second half vias are joined together to formfull vias.
 2. The cable assembly of claim 1, wherein the first cableincludes a main cable portion extending from the first end part, and afurther end part extending from the main cable portion.
 3. The cableassembly of claim 2, wherein the second cable includes a main cableportion extending from the second end part, and a further end partextending from the main cable portion.
 4. The cable assembly of claim 3,wherein the first cable includes a different number of layers from thesecond cable.
 5. The cable assembly of claim 3, wherein the first cableincludes the same number of layers as the second cable.
 6. The cableassembly of claim 3, wherein the main cable portion of the first cablehas the same width as the main cable portion of the second cable.
 7. Thecable assembly of claim 3, wherein the main cable portions of the firstand second cables are stacked together in a thickness direction of themain cable portions.
 8. The cable assembly of claim 1, wherein theconnector assembly is a VHDM connector assembly.
 9. The cable assemblyof claim 1, wherein: the vias include signal vias for receiving thesignal pins and ground vias for receiving the ground pins; the signalvias form a plurality of signal columns, each column extending in thewidth direction of the connector assembly; the ground vias form aplurality of ground columns, each column extending in the widthdirection of the connector assembly; and the full vias receive theground pins.
 10. The cable assembly of claim 1, wherein the firstperiphery of the first end part and the second periphery of the secondend part are coupled together, so as to form a line that passes throughcenters of the full vias along the width direction of the connectorassembly.
 11. The cable assembly of claim 1, wherein: the vias includesignal vias for receiving the signal pins and ground vias for receivingthe ground pins; the signal vias form a plurality of signal columns,each column extending in the width direction of the connector assembly;the ground vias form a plurality of ground columns, each columnextending in the width direction of the connector assembly; and the fullvias receive the signal pins.
 12. The cable assembly of claim 1,wherein: the first periphery of the first end part has a further portionthat has a plurality of third half vias that collectively form a rowalong a length direction of the connector assembly; the second peripheryof the second end part has a further portion that has a plurality offourth half vias that collectively form a row along a length directionof the connector assembly; and the third half vias and the fourth halfvias are joined together to form further full vias.
 13. The cableassembly of claim 12, wherein the first periphery of the first end partand the second periphery of the second end part are coupled together soas to form a line therebetween, the line including a first portion thatpasses through centers of the full vias formed by the first and secondhalf vias along the width direction of the connector assembly, and asecond portion that passes through centers of the full vias formed bythe third and fourth half vias along the length direction of theconnector assembly.
 14. The cable assembly of claim 1, furthercomprising at least one further cable, said at least one further cablehaving an end part, the end part having vias for receiving the signalpins and the ground pins, the vias being disposed to correspond to thesignal pins and ground pins, a periphery of an end of said at least onefurther cable having a portion that has a plurality of half vias thatcollectively form a column along the width direction of the connectorassembly, and wherein the end part of said at least one further cableand the first and second cables are coupled together, such that halfvias of two adjacent end parts are joined together to form full vias.15. A cable assembly for interconnecting a plurality of circuit boardstogether through a connector assembly connected to a circuit board, theconnector assembly having a plurality signal pins and a plurality ofground pins disposed in a plurality of columns, each column extending ina width direction of the connector assembly, the cable assemblycomprising: a connecting portion connected to the connector assembly,the connecting portion having signal vias for receiving the signal pinsand ground vias for receiving the ground pins, the signal vias and theground vias being disposed to correspond to the signal pins and theground pins, the connecting portion being split into at least two partsincluding a first connecting part and a second connecting part, the atleast two part being connected to the same connector assembly; a firstcable portion connected to the first connecting part; and a second cableportion connected to the second connecting part, wherein: at least oneof the signal vias or the ground vias is divided into two or moresections, with the two or more divided sections being disposedcollectively to form a full via.
 16. The cable assembly of claim 15,further including a third connecting part extended from the first cableportion and connected to a further connector assembly, and wherein thefirst cable portion and the first and third connecting partscollectively form a first cable.
 17. The cable assembly of claim 16,further including a fourth connecting part extended from the secondcable portion and connected to the further connector assembly, andwherein the second cable portion and the second and fourth connectingparts collectively form a second cable separable from the first cable.18. The cable assembly of claim 15, wherein the cable assembly is a flexcable.
 19. The cable assembly of claim 15, wherein the connectorassembly is a VHDM connector assembly.
 20. The cable assembly of claim15, wherein: the signal vias form a plurality of signal columns, and theground vias form a plurality of ground columns; each of the signal andground columns extends in the width direction of the connector assembly;and the connecting portion is split such that at least one of the groundcolumns is divided into two regions, one region being included in thefirst connecting part, the other region being included in the secondconnecting part.
 21. The cable assembly of claim 15, wherein: the signalvias form a plurality of signal columns, and the ground vias form aplurality of ground columns including a first ground column and a secondground column; each of the signal and ground columns extends in thewidth direction of the connector assembly; and the connecting portion issplit along a split line including a first portion, a second portion anda third portion, the first portion passing through centers of the viasof the first ground column, the second portion passing through centersof the vias of the second ground column, the third portioninterconnecting the first and second portions.
 22. The cable assembly ofclaim 15, wherein: the signal vias form a plurality of signal columns,and the ground vias form a plurality of ground columns including a firstground column and a second ground column; each of the signal and groundcolumns extends in the width direction of the connector assembly; theconnecting portion is split along a split line; and at least one of thesignal vias or the ground vias is divided into three or more sections bythe split line.